Reinforced concrete (RC) columns in buildings often need strengthening either due to defects in the columns themselves, having to support higher loads than those foreseen in the initial design of the structure, or as the result of ageing or accidental damage. There are many methods of columns strengthening such as jackets with their different types. Jackets are often performed at construction sites by primitive methods, without taking into consideration the correct design or the requirements which should be implemented. At this research, two methods of strengthening have been studied experimentally: concrete jacketing and steel cage. The experimental study consisted of twenty specimens of 800 mm height, 100x100 mm cross section, and main reinforcement 4Ø6 mm with stirrups 7Ø4 mm/800mm. The specimens were strengthened by concrete and steel jackets. From the results of obtained capacity and mode of failure, some modifications were implemented on jacket to improve the efficiency of jackets.